检索结果-内蒙古大学图书馆

Luminescence of a GaN grain with a nonpolar and semipolar plane in relation to microstructural characterization

Chinese Physics B 2012年第6期21卷 520-524页

作者：周小伟许晟瑞张进成党纪源吕玲郝跃郭立新 Key Laboratory of Wide Band-Gap Semiconductor Technology School of MicroelectronicsXidian University School of Science Xidian University Flight Automatic Control Research Institute AVIC

We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask. Transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal the effect of SiN on the overgrown a-plane GaN growth. The SiN layer effectively terminates the propagation of the threading dislocation and basal plane stacking faults during a-plane GaN regrowth through the interlayer, resulting in the window region shrinking from a rectangle to a ＂black hole＂. Furthermore, strong yellow luminescence （YL） in the nonpolar plane and very weak YL in the semipolar plane on the GaN grain is revealed by cathodoluminescence, suggesting that C-involved defects are responsible for the YL.

关键词： nonpolar semipolar GaN yellow luminescence

来源：评论

学校读者我要写书评

暂无评论

Multiple Anti-windup Loops under Multiple Activations:Dynamic Case to Enlarge Domain of Attraction

Multiple Anti-windup Loops under Multiple Activations:Dynami...

引用

第三十二届中国控制会议

作者： Xiongjun Wu Ziyang Meng The 802 Institute of Shanghai Academy of Space Flight Technology The Eighth Academy of China Aerospace Science and Technology Corporation Department of Automation Shanghai Jiao Tong Universityand Key Laboratory of System Control and Information ProcessingMinistry of Education of China ACCESS Linnaeus Centre School of Electrical EngineeringRoyal Institute of Technology

ISBN: (纸本)9781479900305

A multiple anti-windup loops under multiple dynamic activations strategy is proposed to enlarge the domain of attraction. This work is parallel to the multiple activation case with static *** traditional anti-windup compensator is activated immediately as the saturation *** was shown recently that,by delaying the activation of the anti-windup mechanism to a certain level,the performance can be improved for the closed-loop *** was further shown that better performance can be obtained by activating an anti-windup mechanism in anticipation of actuator saturation,in comparison with the delayed activation *** paper considers the anti-windup design problem of enlarging domain of attraction under a dynamic multiple activation *** this multiple activation scheme,the anticipatory,delayed and immediate activation mechanism is incorporated in the same framework simultaneously.A furthermore significant performance improvements over both the immediate and delayed activation schemes can be *** proposed dynamic multiple activation scheme established a unified anti-windup framework and can be readily extended to the traditional immediate,delayed and anticipatory activation anti-windup mechanisms.

关键词： Anti-windup dynamic compensator domain of attraction multiple activations

来源：评论

学校读者我要写书评

暂无评论

Radial breathing modes of multi-walled carbon nanotubes by an atomic beam-spring model

引用

science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 940-946页

作者： MIAO ChunYang LI HaiJun GUO WanLin State Key Laboratory of Mechanics and Control of Mechanical Structures and the Key Laboratory of Intelligent Nano Materials and Devices of MOE and Institute of Nano Science Nanjing University of Aeronautics and AstronauticsNanjing 210016China Maintenance Engineering Division Center of Aviation Safety and TechnologyCivil Aviation Administration of ChinaBeijing 100028China

Based on molecular force fields,a new finite element model is constructed for multi-walled carbon nanotubes where the interlayer interactions and C--C bonds are simulated by the elements of piece-wise linear spring and rectangular cross section beam,*** high computation efficiency and atomic reification,the radial breathing modes of multi-walled carbon nanotubes are studied systemically using this *** results show the correspondence between carbon nanotube structures and vibrational modes,which provide unequivocal data for the experimental characterization of carbon *** empirical relationship of radial breathing modes frequencies with the nanotube radius are also obtained for two-layer carbon nanotubes.

关键词： radial breathing modes multi-walled carbon nanotube atomic beam-spring model

来源：评论

学校读者我要写书评

暂无评论

Multiple Anti-windup Loops under Multiple Static Activations:Enlargement of the Domain of Attraction

Multiple Anti-windup Loops under Multiple Static Activations...

引用

第三十二届中国控制会议

ISBN: (纸本)9781479900305

Anti-windup design is an intuitive and efficient way to deal with input saturation *** the classic antiwindup design,the compensator is set to be activated immediately as the control signal saturates the *** important innovation in the anti-windup activation mechanism is to delay the activation of the anti-windup mechanism until the saturation reaches to a certain severity which led to a performance improvement of the resulting closed-loop *** recently,it was shown that by activating a static anti-windup mechanism in anticipation of actuator saturation,significant further performance improvements can be achieved in comparison with the delayed activation *** addition,we have combined both the delayed and anticipatory activation mechanisms,to develop the multiple activation strategy,in terms of(?) gain *** paper furthermore considers the problem of enlarging domain of attraction and demonstrates that the multiple activation of a static multiple feedback anti-windup mechanism would also lead to significant performance improvements over both the immediate and delayed activation schemes.

关键词： Actuator saturation anti-windup anticipatory activation domain of attraction multiple activation

来源：评论

学校读者我要写书评

暂无评论

Research on spiral motion of guided projectiles based on flight data

Research on spiral motion of guided projectiles based on fli...

引用

4th International Conference on Mechanical and Electrical technology, ICMET 2012

作者： Zhang, Shuang-biao Li, Xing-cheng Su, Zhong Zhao, Liang-yu Beijing Institute of Technology Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education Beijing China Beijing Information Science and Technology University Institute of Intelligence Control Beijing China

ISBN: (纸本)9783037855102

To investigate the realistic spiral motion of a spinning guided projectile, a novel analysis method based on flight data is proposed and further applied. A mathematical model of spiral motion is derived in body coordinate system firstly, and the procedures of the novel method are then described in detail. The spiral motion can be induced by non-zero velocity and rotation rate along the longitudinal axis with at least one non-zero velocity and rotation rate along transverse axes. In the case of non-zero velocities and rotation rates exerted along triple axes, it is observed that the spiral motion consists of single circular motion and double circular motion, and the spiral motion depends on both spinning rate and attitude angles of flight trajectory. © (2012) Trans Tech Publications, Switzerland.

关键词： Projectiles

来源：评论

学校读者我要写书评

暂无评论

A real-time implementation scheme of attitude and velocity algorithms in sins

引用

Information technology Journal 2012年第11期11卷 1650-1654页

作者： Yang, Chun-Ning Ma, Long-Hua Yue, Ya-Zhou Li, Hui School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China National Key Laboratory of Science and Technology on Aircraft Control XlAn Flight Automatic Control Research Institute Xian 710065 China

In this study, a general scheme for implementation of attitude and velocity algorithm in Strapdown Inertial Navigation System (SGNS) urider real-time environment was presented. This real-time implementation scheme was formulated in a recursive form using two time-rate executions and utilized integer arithmetic only. The coding of the attitude and velocity algorithm was conducted by a navigation computer (such as DSP or FPGA). It is shown that the general real-time implementation of strapdown attitude and velocity algorithm can be used in strapdown inertial navigation system for any combinations ofgyro incremental angle sample of mth minor interval and (m-l)thminor interval. © 2012 Asian Network for Scientific Informaction.

关键词： Velocity

来源：评论

学校读者我要写书评

暂无评论

Precision analysis of the semi-strapdown homing guided system

Precision analysis of the semi-strapdown homing guided syste...

引用

AIAA Guidance, Navigation, and control Conference 2012

作者： Jianmei, Song Gaohua, Cai Lixia, Kong Jianhua, Fan School of Aerospace Engineering Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education Beijing Institute of Technology Beijing 100081 China China Aerospace Science and Industry Corp. Beijing 100854 China Sichuan Jiuzhou Electric Group Corp Ltd. Mianyang Sichuan 621000 China

ISBN: (数字)9781600869389

ISBN: (纸本)9781600869389

Precision and stability region analysis of the realistic semi-strapdown homing guided (SSHG) system are made. The mathematic model of the parasitic loop of the SSHG system is established. The stability region of friction coefficient, counter electromotive force (EMF) coefficient, and sensor dynamic mismatch of the realistic SSHG system are given via Routh Criterion by analyzing the stability of the parasitic loop. The stability margin of the semi-strapdown homing seeker (SSHS) parasitic loop can be improved mainly by changing the performance index of the seeker tracking control system. With the adjoint technique, the influence patterns of the main system parameters on the guidance precision of the realistic complex SSHG system are analyzed. Numerical simulations indicate that when the parasitic loop is stable, the performance index of the seeker angular loop influences both the root mean square (RMS) miss distance and RMS command acceleration significantly, the performance index of the seeker inner loop has great effect on RMS command acceleration and little influence on RMS miss distance, which provide the foundation for the engineering realization of SSHS. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Friction

来源：评论

学校读者我要写书评

暂无评论

Design of multiple anti-windup loops for multiple activations

引用

science China(Information sciences) 2012年第9期55卷 1925-1934页

作者： WU XiongJun 1,2 & LIN Zongli 3,1 1 Department of Automation,Shanghai Jiao Tong University,and key laboratory of System control and Information Processing,Ministry of Education of China,Shanghai 200240,China 2 No.802 Institute of Shanghai Academy of Space flight technology,the Eighth Academy of China Aerospace science and technology Corporation,Shanghai 200090,China 3 Charles L.Brown Department of Electrical and Computer Engineering,University of Virginia,P.O.Box 400743,Charlottesville,VA 22904-4743,USA 1. Department of Automation Shanghai Jiao Tong University and Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai 200240 China2. No. 802 Institute of Shanghai Academy of Space Flight Technology the Eighth Academy of China Aerospace Science and Technology Corporation Shanghai 200090 China3. Charles L. Brown Department of Electrical and Computer Engineering University of Virginia P.O. Box 400743 Charlottesville VA 22904-4743 USA

This paper considers anti-windup design for linear systems subject to actuator *** anti-windup gains are designed for activations immediately at the occurrence actuator saturation,after the saturation has reached a certain level and in anticipation of the occurrence of saturation,*** design is based on the minimization of L 2 gain from the disturbance to the controlled output of the resulting closed-loop *** anti-windup scheme involves a single anti-windup loop for immediate activation.A recent innovation is to design a single anti-windup loop for delayed or anticipatory activation,as well as to design two anti-windup gains,one for immediate activation and one for delayed *** design of three anti-windup gains for three different activations is shown through simulation to lead to significant further performance improvement over the previous activation schemes.

关键词： actuator saturation anti-windup anticipatory activation delayed activation L 2 gain nonlinear control

来源：评论

学校读者我要写书评

暂无评论

Design and application of wireless signal strength measurement system on the near-ground

引用

Journal of Measurement science and Instrumentation 2012年第3期3卷 205-210页

作者：孔祥善师新蕾王代华张志杰 North Automatic Control Technology Institute China North Industries Group Corporation Aero-instrument Co.Ltd. Aviation Industry Corporation of China Key Laboratory of Instrumentation Science and Dynamic Measurement(North University of China) Ministry of Education

The wireless communication system's performance is greatly constrained by the wireless channel characteristics,especially in some specific ***,signal transmission will be greatly impacted even if not in a complicated *** results show that it is hardly to characterize the radio propagation properties for the antenna installed on the *** order to ensure a successful communication,the radio frequency(RF)wireless signal intensity monitor system was *** can get the wireless link transmission loss through measuring signal strength from received *** test shows that the near-ground wireless signal propagation characteristics still can be characterized by the log distance propagation loss *** results will conduce to studying the transmission characteristic of Near-Earth wireless signals and will predict the coverage of the earth's surface wireless sensor network.

关键词： near-ground wireless signal transmission received signal strength test radio frequency(RF)wireless channel modeling

来源：评论

学校读者我要写书评

暂无评论

Optimal placement for gravitational tractor in trajectory deflection mission of small bodies

引用

Guangxue Jingmi Gongcheng/Optics and Precision Engineering 2012年第SUPPL.期20卷 86-93页

作者： Jin, Ting Shang, Hai-Bin Wang, Shuai Huang, Xiang-Yu Key Laboratory of Dynamics and Control of Flight Vehicle of the Ministry of Education School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China Science and Technology on Space Intelligent Control Laboratory Beijing 100190 China

In order to solve the optimal placement problem for a gravitational tractor in the trajectory deflection mission of small bodies, this paper gives an optimal selection method for the tractor placement based on a hybrid optimization strategy. First, the movement of small bodies is modeled based on the modified equinoctial orbital element, and the position of gravitational tractor related to small bodies is regard as the control angle to small bodies. Then, an optimal control angle is derived based on the maximum principle, and the selection problem for placement is changed into an optimal problem for the initial value of the costate. In order to obtain the global optimal solution, the differential evolution algorithm is used to do a wide range of initial search for the optimal model, furthermore, sequential quadratic programming algorithm is used to obtain the local precise optimization. By taking high-risk small body Apophis as an example, the proposed method is verified. Numerical results demonstrate that the optimal placement for the gravitional tractor oscillates near the direction of small bodies' velocity and gravitional tractor can effectively deflect the small bodies.

关键词： Quadratic programming

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：